1. Field of the Invention
This invention relates to a method of and means for raising both the base rim and the cover of a manhole, catch basin, or other cast structure surrounded by pavement. The geometry of the rim and cover permit the use of a one-piece adapter which is itself cast entirely of the same material as the rim and cover. Further, the adapter allows the rim and cover elevation to be quickly raised by an amount less than the thickness of the cover, without requiring the removal of the surrounding pavement.
2. The Prior Art
Castings in newly paved areas ordinarily have rim elevations equal to the finished elevation of the pavement adjacent to the structure. If the pavement includes a bituminous section, the final lift of pavement (the wearing course) may not be installed for a year or more. During this time, castings which are in the bituminous pavement are left high to accommodate the ultimate placement of the wearing course. Such castings constitute an obstacle to pedestrian and vehicular traffic. Further, the lip created by the raised casting obstructs street scraping and cleaning operations as well as snow plowing, and impedes storm water drainage if the structure is part of the storm system.
One method of renovating the surface of a road is to place a bituminous overlay over the existing paving. Unless the overlay is thicker than the respective covers of structures within the overlay, the existing pavement must be removed from around the structure to allow the rim and cover elevation to be raised with shims. The adjusted structure elevation will then accommodate the placement of the overlay. Pavement that was removed to facilitate placement of the shims is replaced prior to placement of the overlay, which then serves as a new wearing course. This process is both time-consuming and costly, and causes additional congestion and potential for liability for workers renovating the road and for drivers frequenting the road.
An alternate method of renovating the surface of a road consists of removing the top layer of the road""s surface and replacing the top layer with a new bituminous wearing course. The removal of the top layer of paving can be accomplished by milling the road""s surface, but paving immediately adjacent to the structure requires hand work to remove. This process also involves extra time, additional expense, and increases traffic congestion and potential for liability.
In an effort to diminish such traffic congestion and potential for liability, and at the same time to reduce paving budgets, some municipalities have begun to use adapters which incorporate relatively thin steel segments. Alternately, the municipality or developer simply directs the paver to taper the overlay to meet the rim of the structure at its original grade.
The thin steel segments allow a method of quickly raising rim elevations a minimal amount, but introduce possible problems with regard to structural strength, access, and corrosion resistance.
The structural strength of the new adapters which incorporate thin steel segments is suspect, given the pounding the structure is subject to while the asphalt overlay is being placed, and impacting by snow plows and vehicle traffic. The adapter may not fail entirely, but may warp sufficiently to make removal and replacement of the cover problematic. Many such adapters require the use of protruding setscrews to secure the adapter to the rim below. The setscrews reduce the effective open area of the casting, and can be the cause of injury or damage to personnel or equipment entering or exiting the manhole.
Similarly, introducing a dissimilar metal such as steel between the rim and the cover is an invitation to galvanic corrosion, particularly in those areas which use rock salt or a similar material to treat snow and ice buildup on road surfaces.
Numerous solutions have been proposed in an effort to facilitate the adjustment of the rim elevation, as follows:
Pavement is removed adjacent to the structure, and shims are inserted under the casting to bring it to the proposed elevation of the wearing course. This method is commonly practiced on construction sites now, and further refinements are disclosed in patents such as U.S. Pat. No. 5,934,820 to Vernon W. Hinkle, U.S. Pat. No. 5,564,855 to Dennis C. Anderson, and U.S. Pat. No. 5,470,172 to Dwight G. Wiedrich.
Manipulation of the casting within the pavement, a method which purports to allow vertical adjustment of the rim elevation without disturbing the surrounding pavement, frequently fails in the field, possibly resulting in delays in paving the surrounding area. This technique is taught in U.S. Pat. No. 5,451,119 to John L. Hondulas, U.S. Pat. No. 5,318,376 to Everett J. Prescott, Sr., and U.S. Pat. No. 5,095,667 to Chester Ryan.
The casting is raised by manipulation of threaded bolts, as shown in U.S. Pat. No. 5,344,253 to Cesare Sacchetti, U.S. Pat. No. 4,925,337 to Hansruedi Spiess and Francoix Galvanetto, and U.S. Pat. No. 4,149,816 to Johannes L. Piso. These designs subject the casting to extreme point loading at each of the adjustment bolts, and create an opportunity for both mechanical failure and/or corrosion at each such bolt. Similarly, designs have been proposed which allow convenient adjustment of the elevation of the rim by the incorporation of steps in castings which mate in making up the rim as a whole. U.S. Pat. No. 5,360,131 to Guy M Phillipps and Wayne A Harris, U.S. Pat. No. 5,211,504 to Roger Trudel, and U.S. Pat. No. 4,906,128 to Roger Trudel all propose variations of steps in adjoining castings; and all impose point loading at the step locations in a manner similar to the point loading caused by the adjustment bolts as indicated above.
The cover elevation is raised by the insertion of a cylindrical shim under the cover. Here, a cylindrical section is added outside the perimeter of the cover to raise the elevation of the rim. Prior-art teachings frequently show the shim for the rim to be made of an insubstantial material, either disassociated from the cover shim entirely or connected with a thin strip of metal to facilitate the re-use of the original cover. U.S. Pat. No. 5,899,024 to Edward C. Stannard, U.S. Pat. No. 5,769,564 to David John Drake Hawkins, and U.S. Pat. No. 5,308,189 to Jean-Louis Claing all teach the use of such designs. The rim shim is prone to damage or destruction by vehicular traffic, snow plows, etc., due to its light section and marginal connection to the underlying cover shim. In many instances, the construction of the shim assembly results in the mating of dissimilar metals, and subsequently suffers the accelerated corrosion attendant upon such mating.
Numerous other methods have been advocated to facilitate the adjustment of structure elevations within pavement areas; none have achieved widespread acceptance for a variety of reasons, some of which are mentioned above. The ideal solution would permit the structure to remain flush with the surrounding pavement for an indeterminate period, and would permit the rapid adjustment of the elevation of both the rim and the cover immediately prior to milling or paving, without causing excessive delays to traffic and unnecessary expenses to the developer or municipality. Perhaps most importantly, the danger to motorists dodging traffic barricades and to workers protected by the barricades will be minimized, as casting elevations can be adjusted in minutes rather than days.
The invention provides an assembly for adjusting the elevation of a structure such as a manhole or a catch basin having a base rim surrounded by pavement, the base rim comprising an outer wall and a support shoulder extending inwardly from the wall and spaced downwardly from an upper end thereof. The assembly comprises a cover, and an adapter formed in a single piece to support the cover thereon and having upper and lower members. The lower member is receivable within the wall of the base rim to be supported on the shoulder thereof, the upper member extending outwardly of the lower member to receive the cover therewithin and upwardly to engage the upper end of the base rim and form an upward extension thereof. The lower member is formed with a plurality of inwardly extending protrusions distributed to form spaces therebetween and interconnecting the upper and lower members to form steps at the protrusions. The cover is receivable within the upper member to be supported on the lower member, the cover being formed with a plurality of indentations in a lower surface thereof, the indentations being dimensioned and disposed to receive the adapter protrusions therewithin. Portions of the cover above the indentations are dimensioned and disposed to be supported on the steps. With this construction, the elevation of the structure may be increased by supporting the assembly on the base rim of the structure and decreased by removing the adapter from between the base rim shoulder and the cover.
The vertical dimensions of the adapter may be calculated to raise the elevation of the structure through a distance smaller than the thickness of the cover when the adapter is inserted between the base rim and the cover.
The assembly may include one or more additional adapters of identical construction with the first, all the adapters being formed to nest within one another, the elevation of the structure thus being dependent upon the number of adapters inserted between the base rim and the cover.
Where the structure is a manhole, the base rim, the adapter and the cover are of generally cylindrical form.
On the other hand, where the structure is a catch basin, the base rim, the adapter and the cover are of generally rectangular form.
As described above, the assembly may be applied to an existing structure in which the base rim is of conventional configuration. However, for new installations, a base rim may be provided in accordance with the invention in which the base rim shoulder is formed with a plurality of upwardly extending protrusions dimensioned and disposed to be received in the spaces formed by the adapter protrusions in alternating relation with them.
Use of the invention allows pavement to be installed in new road sections without the necessity of leaving structures protruding from the initial lift or lifts pending installation of the final wearing course, which may not occur for a year or more
The invention facilitates adjustment of the rim elevation of structures in paved areas which are to receive an overlay, without requiring the removal of pavement around the structure
The invention also facilitates removal of the top layer of pavement adjacent to structures in paved areas by milling rather than requiring handwork.
The invention provides complete drainage around storm structures in the above circumstances, including those structures which may be located partially in a concrete curb and gutter and partially in a bituminous paving section
The invention allows rim elevation adjustment to be accomplished quickly and accurately minutes before the wearing course or overlay is placed
In short, the unique geometry of rims, covers, and adapters according to the invention permits the rapid adjustment of the elevation of manholes, catch basins, and other structures within paved areas. Such elevation adjustment can be accomplished without having to remove pavement or curb and gutter. Further, the unique geometry allows the adjustment to be carried out in minutes, just before the placement of new paving adjacent to the structure.
This ability reduces the danger to highway construction crews and motorists, reduces necessary funding for paving projects, and reduces traffic congestion caused by road repairs.
These and other features and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings.